1. Field of the Invention
This invention relates to a radiometric analyzer for precisely measuring by radiation the various characteristic values of a sample.
2. Description of the Prior Art
Radiometric analyzers for measuring characteristic values of a sample by radiation are known. However, in such analyzers, the calibration of measuring error dependent upon the difference of content ratio of the sample is not realized or is incomplete. The error depending upon the difference of content ratio of the sample is, for example, error due to the CH ratio in the case of measuring the density of hydrocarbons by gamma ray densitometer.
When the density of hydrocarbons is measured by utilizing the absorption of gamma rays, it is preferable that the degrees of absorption of the gamma rays by carbon and hydrogen are proportional to the masses of carbon and hydrogen. In practice, however, the mass absorption coefficient of gamma rays per mass of hydrogen is about two times higher than that of carbon. Accordingly, the mass of hydrogen is erroneously overestimated. This error is referred to as error due to the CH ratio.
In the conventional technology for overcoming this error, there is a method of using an X ray source or a gamma ray source having specific energy to provide equal mass absorption coefficients of carbon and hydrogen (about 20 KeV). In this case, 241 Am--Ag, 147 Pm--Al and the like are used as the ray sources. However, this is not completely monochromatic with the result that the energy spectrum is disadvantageously varied by absorption depending upon the sample and the effective energy is undesirably varied.